Maxtor 10K III manual 218, Write Buffer Command Descriptor Block-Data Format

SCSI Description

￿￿￿￿94+6'The ￿WRITE$7(('4BUFFER￿%QOOCPFand the￿￿￿READ$J￿BUFFER commands allow the initiator to gain access to the data storage areas within the drive controller. These commands are used to check the integrity of the buffer-initiator data path independent of the storage medium, typically for fault isolation. The commands can be used to verify the caching policies of the controller or other kinds of debug work. In addition, the WRITE BUFFER command supports controller microcode downloads. The data format and field descriptions are shown in Table 5-218and Table 5-219respectively.

Both the READ BUFFER and WRITE BUFFER commands have a Buffer ID and a Buffer Offset data field defined in their Command Descriptor Block. In combined Header and Data Mode, if both are set to 0, reference is made to a single, 512-byte buffer set aside in the controller's data memory, independent of cache. This allows an initiator to verify the data path from the controller's data memory to the initiator without affecting the drive's internal data caches.

WRITE BUFFER Command Descriptor Block-Data Format

$[VG0$KV	￿	￿		￿	Operation￿Code￿(3Bh)		￿		￿	￿
1			Reserved					Mode
2						Buffer ID
3 - 5						Buffer Offset
6 - 8					Parameter List Length
Table9	5-218					Control

Maxtor Atlas 10K III 5-173